Cytochalasin B (= CCB, Phomin) in several concentrations inhibits the visible movement of gregarines. The fine structure of the cell is simultaneously changed, fibrillar bundles are desorganized. These fibrils are regarded as myonemes. 2. These myonemes are directed peripherally of the cell longitudinal and transverse to its axis. The longitudinal myonemes are organized in separated strings stretching along the top of the epicyte folds, between the plasmalemm and the secondary membranous layer. Fibrils under this layer serve as skeleton and as thus antagonist. The skeleton fibrils remain unaltered after CCB inhibition. They are located in a parallel direction to the myonemes. Their number corresponds together in one epicyte fold. The transverse myonemata surround the central plasma nearby the basal lamella, which cannot be found in some of the regarded species. 3. The co-work of skeleton-fibrils, stiff pellicle and myonemes allows to describe the modus of all known types of movement. Only change of coordination yields the multitude of these kinds of movement.
